Commercial, Public Service, Regulatory

Broadening the Base

By James T. McKenna | August 1, 2005
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With two teams working on firefighting tanks for the K-Max--and one on the verge of certification, operators may have a new reason to order the strange but uniquely capable aircraft. Kaman hopes so.

SUPERIOR HELICOPTER MIGHT HAVE BEEN FLYING ITS new FIREMAX helicopter weeks ago. But business was just too good.

The Grants Pass, Ore.-based logging, construction and firefighting helicopter operator and its partner, Kawak Aviation Technologies, had been progressing nicely toward certification of that new helicopter. More than 100 water drops had been performed, proving the design and flight characteristics of the aircraft. The FAA was just three days away from having a test pilot fly it and sign off on a supplemental type certificate for Kawak's installation.


Then on June 21, a week after the K-MAX fitted with a 700-gal. (2,660-L.) water tank had made its first flight, Arizona's Cave Creek Complex started to burn.

Superior is the largest operator of Kaman Aerospace's K-MAX, with its narrow body and intermeshing rotors. The company owns four of them, and on occasion has leased a couple more. But three of the helicopters were committed to jobs when the call came in for support in fighting the wild fire at Cave Creek that would burn nearly 244,000 acres (98,740 hectares). So the fourth K-MAX had to go to work, and FIREMAX certification had to wait a bit longer.

You might forgive Superior, Kawak and Kaman for being a bit impatient to get back to the project that they've been working on for the last year. All three see FIREMAX as a means to expand their respective markets and vie more effectively with competitors.

For Superior, adding FIREMAX's new capabilities to its arsenal could mean new firefighting contracts with the U.S. Forest Service and with agencies in Australia. "We've worked hard to increase the profile of the K-MAX with the Forest Service and in Australia," said Andy Mills, assistant general manager at Superior.

For Bend, Ore.-based Kawak, the project is an opportunity to graduate from building tank components to making, selling and servicing the tanks themselves. It has developed auxiliary hydraulics for tanks on Carson Helicopters' S-61 Fire King, Kroman's firefighting S-61 and the Los Angeles County Fire Dept.'s Bell 412s.

"We had a pretty good handle on what it took to develop an auxiliary hydraulic system" to operate tank pumps and water-release doors. "If Superior had selected someone else for the project, the other manufacturers would have been buying parts from us," said Mike Reightley, Kawak's president and project manager. "The missing element was building the shell [of the tank] ourselves."

For Kaman, Kawak's tank (particularly if proven operationally by Superior) could increase the utility of the K-MAX for current operators and increase its appeal for potential customers. "We're encouraging it," said Roger Wassmuth, Kaman's director of K-MAX marketing and business development. "We think this is going to be a pretty good product for someone."

Certified in 1994, the K-MAX is designed for repetitive external lifting, specifically for vertical reference flight. It has a 5,000-lb. (2,268-kg.) on-the-hook lift capacity at 8,000 ft. altitude (2,446 m.) and 6,000-lb. (2,722-kg.) at lower altitudes. According to Kaman, the aircraft has been used successfully for firefighting, construction, logging, counterdrug logistics support operations and other specialized utility missions.

Kaman last year halted K-MAX production when its order book was filled. The company is looking to package a number of separate orders with a sufficient quantity of aircraft to justify restarting the line.

(Another company, Isolair, Inc., of Troutdale, Ore., is developing a composite tank fitted to the K-MAX. Kawak's, though, is the lead project.)

But why do Superior, Kawak and Kaman see such bright prospects for a K-MAX with a fixed tank? To answer that, say, "Whoo-ee"--as in WUI, or wildland-urban interface. This is the name of those areas around the United States, growing in number and in scope, where urban and suburban development encroaches upon wildland areas. Homeowners like the house values and the scenery there, until they see fast-moving, deadly wildfires coming.

These interfaces are a top concern of firefighting officials in the United States, and that presents problems for operators of firefighting helicopters--or opportunities, depending on your viewpoint.

Because fires at these interfaces are near heavily populated areas, agencies like the U.S. Forest Service that oversee firefighting operations do not want to use helicopters slinging buckets from long-lines in combating them. They want the comfort and safety of fixed-tank aircraft. "More and more firefighting is going to be taking place in the WUI," said Superior's Mills. "It's an issue in the Los Angeles Basin, in the San Diego area, in the foothills around Denver and in the Wasatch Range around Salt Lake City." A K-MAX with a fixed tank will get Superior firefighting contracts it might otherwise be locked out of.

Not that Superior is giving up on long-line work.

"We have no intention of not flying the K-MAX with a long-line and bucket where we can," Mills said. "It's got superb visibility. It was built for vertical-reference work."

Setting the K-MAX up for fixed-tank operations posed many challenges.

The customer dictated some, as Mills explained. Superior wanted a tank that could be filled quickly, maintained a good center of gravity during filling, flight and drop operations, was reliable and could produce a good water-drop pattern. It also wanted a tank that could be removed and installed in under an hour, could split a 700-gal. water load in two equal drops and would not drop the K-MAX's cruise speed below 90 kt. The last two are Forest Service contract requirements.

Oh, yes, and Superior wanted the tank certificated and ready for operation for this year's fire season.

The aircraft posed its own challenges, according to Reightley. The K-MAX's narrow body has tight lateral c.g. limits; Reightley said they are 1.25-in. wide. That also raised issues that had to be addressed concerning lateral stability (during filling and dropping in side winds and cross winds, and particularly during salvo dumping) and impingement of the rotor downwash on the water-dispersal pattern.

Another challenge was attaching the tank. "It's a unique shape," Reightley said. "There are no hard points other than the main lift beam of the helicopter." In addition, he said, the K-MAX tends to fly nosedown. "We didn't want to exacerbate that."

More than 100 water drops--first flown by Superior's assistant chief pilot, John Vogan, on June 14 and by him and others thereafter--have convinced the team Kawak's design met those challenges, and then some.

"We wanted a state-of-the-art system," Mills said, "and I believe that's what we've got."

"A lot of it was knowing how to wrap 700 gal. around that helicopter," Reightley noted.

The U-shaped, 6-ft.-long, 5-ft.-tall Kawak tank is made of 6065 aluminum, with all its ribs and spars CAD/CAM-machined from solid blocks of aluminum for better strength-to-weight ratio. All its load-bearing frame parts are machined with a 5-deg. radius on the inside flanges for very high strength. The entire system, including hydraulics, weighs 640 lb. Kawak's objective is to get that down on the next tank. (Parts for the second tank already have been assembled and Kaman has said it "will make every effort" to put that tank into service this year, too.)

In addition to providing blueprints and engineering support, Kaman assisted in the effort by gaining an increase in the K-MAX's maximum gross takeoff weight--approved in June--from 6,500 to 7,000 lb. That meets Forest Service requirements, Wassmuth said, and will allow K-MAX users to operate the aircraft with the tank in the Normal aircraft category.

The increase requires a tradeoff in terms of "a very small reduction" in the life of the K-MAX's rotor hubs, based on a worst-case mission profile of 30-40 lifts each hour, Wassmuth said. Beyond the hubs, "very few components were impacted."

The tank system includes a 35-gal. integral foam injection reservoir and a hydraulic-powered hover refill pump that is run off an existing 50-hp. accessory pad on the helicopter's transmission. This eliminates the need for heavy electrical system components and the associated maintenance and parts required to service them.

Reightley said the pump can refill the tank in 22-25 sec., "less time than it takes some pilots to get the snorkel to sink."

The tank's aerodynamic fairings are made of Kevlar/carbon fiber laminate for strength and low weight and designed to produce enough lift to offset any nosedown moment created by a full or partial water load. The FIREMAX has demonstrated a cruise speed of 95-100 kt., he said. The standard K-MAX cruises at 100 kt.).

The tank's high sides and narrow, long doors provide excellent hydrostatic head pressure and an extremely dense water column for very effective drop patterns. The head pressure created by the configuration required a beefier structure for the doors, Reightley said. They are made of one-piece milled aluminum for high strength and reliability and powered by custom-built rotary hydraulic actuators.

The tank system's computer monitors all loads, drops and fills, and that data can be downloaded at the end of the day. The computer can be programmed for multiple, metered drops at six different coverage levels and drop patterns. The pilot also can manually control drops.

At the lowest coverage setting, Kaman said, the FIREMAX can lay water in a steady "waterfall" for 45 sec., creating a curtain of water along the leading edge of fast moving fires and grassfires.

At the "salvo" or highest volume setting, the tank empties in 3.5 sec. for a very concentrated column of water. According to Kaman, the K-MAX is one of the few helicopters that has enough power to come to a hover before a full salvo drop, increasing the accuracy of the drop. Reightley said at the high-concentration setting, the FIREMAX will produce a drop pattern on the ground 15 ft. wide.

The tank is attached to two lugs on the K-MAX's main lift beam.

With an STC for the installation in hand, Reightley said, Kawak will have "a good opportunity to announce to the helicopter firefighting community that, `Hey, there are some other choices.'"

Superior already has bid on Australian firefighting contracts on which it would use the FIREMAX. "Once we get FAA certification, we can offer it to the Forest Service," Mills said.

Wassmuth said the FIREMAX configuration, once approved, should create a number of prospects for additional sales. He said he anticipates international fleet sales. In addition to acquisitions of brand-new K-MAXs equipped with the Kawak tank system, he said, existing K-MAX operators may purchase and install tank systems from Kawak to further expand the utility of their present aircraft.

There also may be applications beyond firefighting, he said, noting that "the U.S. State Dept. is looking to do more and more with their K-MAXs down in Colombia." With a tank in place to carry water for firefighting purposes, he said, it's not a great stretch to envision external fuel tanks to increase the range and mission capabilities of utility K-MAXs.

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